May 2016

The Hot Topic

We’ve seen a significant shift in how we construct and retrofit properties in the UK. With government targets to reduce energy consumption in buildings by 80% by 2020, it is only logical to focus investment on insulation and double-glazing. Whilst this is fantastic for thermal and acoustic performance – it’s not for indoor air quality. This is because without an efficient ventilation system, increased air-tightness can lead to damp, mould, condensation and the associated effects.

Without the extraction of excess moisture and the filtration of clean air, damp and mould can spread quickly – causing damage to the building fabric that can be costly and often time consuming to repair.

Even more worrying is the harmful effect poor indoor air quality can have on health. Research has proven that people living in homes with inadequate ventilation are more likely to suffer from headaches, allergies and respiratory illnesses. Considering people spend around 90% of their time indoors, ensuring high quality indoor air is circulated throughout a home must be a priority.

Those responsible must ensure that ventilation systems are compliant with Approved Document F of the Building Regulations, which stipulates that different rooms in various dwellings require varying intermittent ventilation rates. This is because kitchen and bathroom areas will have higher levels of moisture in the air from everyday activities such as cooking and showering.

Here’s a useful guide that shows the recommended volume of air extraction per room as suggested by the Building Regulations:

  • Toilet/sanitary accommodation 6 l/sec (22 m3/hr)
  • Bathroom/shower room 15 l/sec (54 m3/hr)
  • Kitchen adjacent to hob 30 l/sec (108 m3/hr)
  • Kitchen without cooker hood 60 l/sec (216 m3/hr)
  • Utility room 30 l/sec (108 m3/hr)

When looking at bathrooms and kitchens it is also imperative to specify fans that achieve the required performance after the fan is fitted, with the appropriate ducting or grilles in place. This is called ‘installed performance’ and is again compulsory.

In addition, as our buildings are now being designed to reduce heat loss and be increasingly airtight - overheating in the summer months has become a serious concern.

A survey carried out by WSP Parsons Brinckerhoff revealed over 80% of people living in London were found to have suffered from overheating in their homes last summer.

Whole home Mechanical Ventilation with Heat Recovery (MVHR) technology can help reduce the risk of overheating as well as address indoor air quality. It provides a practical option for a new build or refurbishment scenario. Where overheating is a real concern – it is also crucial that the MVHR system utilises a 100% bypass function. This will ensure the MVHR unit can reduce solar gain by ensuring the supply air is not heated by the hot extract air passing through the heat recovery core.

With a plethora of challenges, issues and regulations in place it is more critical than ever to seek professional guidance on appropriate and effective ventilation. Only then can we have a positive impact on indoor air quality and comfort levels, as well as improve the efficiency of our homes.